I have a wife and a boy and girl, almost identical in age to the Miyazawa children. There are other families, similar to the Miyazawas, that reside where the killer is now. While I don't believe the killer has killed since leaving Japan, I completely believe he's capable of doing so again. For public safety, he needs to be at least identified. Then, let TMPD act as they will.
TMPD is doing a huge disservice, not only to the Miyazawa family, but to unbeknownst families who are currently in the killers path. I don't know if the stereotype of Japanese shame truly exists. Regardless, there's going to be an extreme level of that when the public is made aware of this, which I suspect will be soon. As much as Nic respects the Chief, his failure to catch the killer, whilst a novelist and a group of armchair sleuths staying up late at night in their American basements do, will unfortunately be "Chiefs" lasting legacy.
In Faceless, Nic briefly touched on an incident where he thought the killer might be right outside his window. While he quickly brushed off the idea, it's not completely far fetched. He's also stated on this forum that while he doesn't think he'll come after him, he's ready if he does. These thoughts are actually quite rational.
A quick Google search prompts Faceless, this forum, and others showing things beginning to narrow down the killer. Surely he has to have looked at some. And as the case continues to build, I suspect so too does his tension. It's very logical to assume he'll act on it.